The present invention relates to a process for the contacting of a wire conductor in the course of the manufacture of a transponder unit arranged on a substrate and comprising a wire coil and a chip unit and a device for implementing the process and a device for the wiring of a wire-shaped conductor on a substrate.
In particular in the course of the manufacture of transponder units arranged on a substrate and comprising, by way of essential elements, a wire coil and a chip unit which has been contacted with the ends of the coil, the contacting of the ends of the coil with the terminal areas of the chip unit proves to be a particular problem. This is mainly due to the very small dimensions of the components to be connected to one another. For instance, the terminal areas of a chip unit, which as a rule are of square or approximately square design, customarily have an edge length of about 100 to 150 xcexcm By way of coil wire, particularly for the purpose of forming low-frequency coils, use is made of a copper wire having a diameter which as a rule amounts to around 50 xcexcm-.
As can be gathered from WO 91/16718 for instance, in the past a direct contacting of the ends of the coil wire with the terminal areas of a chip unit has been circumvented through use being made, by way of coupling element between the ends of the coil wire pertaining to a wire coil arranged on a coil substrate and the terminal areas of the chip unit, of a contact substrate comprising enlarged terminal areas, so that by virtue of the contact faces of the contact substrate that are very large in comparison with the diameter of the coil wire a contact could be brought about without making great demands as regards the precision of the relative positioning between the ends of the coil wire and the contact faces. Since with the known process the chip unit is equipped with additional contact conductors for the purpose of making contact with the enlarged terminal areas of the substrate, in the case of the manufacturing process known from WO 91/16718 a total of at least three contacting steps are required in order finally to establish an electrically conductive contact between the terminal areas of the chip unit and the wire coil.
The object underlying the invention is therefore to propose a process and also a device enabling direct contacting of wire ends on the terminal areas of a chip unit.
With the process according to the invention, in the course of the manufacture of a transponder unit arranged on a substrate and comprising a wire coil and a chip unit, the coil wire is guided in a first process step via the assigned terminal area of the chip unit, or a space that is intended to accept this terminal area, and is fixed to the substrate. By this means an exactly defined alignment of the coil wire relative to the terminal area is obtained after the first process step has been carried out. In the second process step the connection of the wire conductor to the terminal area is then effected by means of a connecting instrument.
By virtue of the process according to the invention there is no longer any necessity, with a view to bringing the terminal areas of the chip unit into contact with the ends of the coil, to provide a separate contact substrate on which enlarged terminal areas are formed. Rather, the coil substrate, which is used in any case as substrate for the wire coil and which, for example in the case where the transponder unit is intended to serve for the manufacture of a chip card, is formed by means of a plastic support sheet corresponding to the dimensions of the chip card, serves virtually as a contacting or positioning aid for the relative positioning of the ends of the coil in relation to the terminal areas of the chip unit. In this case the chip unit may either be arranged in a recess in the substrate provided for this purpose or may be provided on the surface of the substrate. The first alternative affords the possibility of arranging the chip unit in the recess optionally prior to fixation of the wire conductors or of introducing the chip unit into the recess only after fixation of the wire conductors, in order subsequently to implement the actual contacting of the wire conductors on the terminal areas.
By virtue of the wire conductors which are fixed on the coil substrate the process according to the invention consequently enables simplified contacting of the wire conductors with the terminal areas of the chip unit.
With one variant of the process, which independently of for bringing a terminal area into contact with a wire conductor also enables an advantageous arrangement of the wire conductor on the substrate, the wire conductor is subjected to the action of ultrasound in a direction transverse to the wiring plane, and the transverse movement of the wiring device induced by the action of ultrasound is superimposed on the wiring movement extending in the wiring plane.
The superimposition of the wiring movement together with the transverse movement countersinking the cross-section of the wire conductor in the surface of the substrate or bringing it into close contact with the latter enables continuous operation of the wiring device, so that the wire conductor is capable ofbeing connected to the surface of the substrate not only in the region of definite connecting points but over any length without the actual wiring movement having to be interrupted in the process. Furthermore, the transverse movement induced by ultrasound proves to be particularly effective during the at least partial countersinking or the close contacting of the cross-section of the wire, since the movement induced by the ultrasound extends in the direction of sinking and not transversely thereto, as is the case with the process described in the introduction.
It proves to be particularly advantageous if the transverse movement induced by ultrasound takes place along a transverse-movement axis that is variable as regards its angle in relation to the axis of the wiring movement. By this means it is possible to adjust the transverse-movement axis so as to conform to the special requirements. Thus it is possible in the case where an elevated temperature of the wire conductor to be countersunk is desired, possibly depending on the substrate material, to align the transverse-movement axis more in the direction of the wiring-movement axis, in order in this way to obtain a greater longitudinal-force component which acts on the wire conductor and which as a consequence of the associated rubbing of the wire guide on the wire conductor results in heating of the same. In order to obtain a rate of sinking of the wire conductor in the surface of the substrate that is as high as possible it can be advantageous to align the transverse-movement axis at an angle of 45 degree. to the wiring-movement axis, in order to achieve a shearing effect in the substrate material that is as great as possible.
In order to vary the depth of penetration of the wire conductor into the surface of the substrate, the ultrasonic frequency and/or the angle between the axis of the wiring movement and the transverse-movement axis may also be varied.
With respect to a connecting process following the wiring of the wire conductor in the form of a wire coil on the surface of the substrate for the purpose of connecting the wire conductor to terminal areas of a chip unit it can prove particularly advantageous if the final region of the coil and the initial region of the coil are guided via a recess in the substrate, so that the subsequent connection of the terminal areas of a chip unit to the initial region of the coil and to the final region of the coil can be effected without impairment caused by the substrate material.
In order to enable an alignment of the initial coil region and of the final coil region that is as rectilinear as possible between opposite edges of the recess it is advantageous to interrupt the exposure of the wire conductor to ultrasound in the region of the recess.
An interruption of the exposure of the wire conductor to ultrasound also proves to be advantageous for the purpose of crossing an already wired section of wire in the crossing region, whereby in addition the wire conductor in the crossing region is guided in a crossing plane that is spaced from the wiring plane. This ensures that a crossing of wire conductors becomes possible without it being possible for damage to occur in the process as a result of collision of the wire conductors, which could possibly result in destruction of the insulation of the wire conductors.
The use of the process described above in various embodiments has also proved to be particularly advantageous for the manufacture of a card module having a substrate, a coil which is wired on the substrate and a chip unit which is connected to the coil. In this case a coil having an initial coil region and a final coil region is formed on the substrate in a wiring phase by means of the wiring device, and in a subsequent connection phase a connection to terminal areas of the chip unit is brought about between the initial region of the coil and the final region of the coil by means of a connecting device.
As a result of the integration of the wiring of the wire conductor on the substrate into a process for the manufacture of a card module on the basis of any substrate that permits an at least partial penetration of the wire conductor into the surface of the substrate or close contact of the wire conductor against the surface of the substrate, this application of the process enables the formation of card modules that are easy to handle and that are used as semifinished products in the manufacture of chip cards. With a view to completion of the chip card the card modules are then, as a rule, provided on both sides with laminated surface layers. Depending on the configuration and thickness of the substrate material, the connection between the wire conductor and the substrate material can be effected via a more or less positive inclusion of the cross-section of the wire conductor in the surface of the substratexe2x80x94for instance, when the substrate is formed from a thermoplastic materialxe2x80x94or by means of a predominantly close-contact fixing of the wire conductor on the surface of the substrate, for instance by bonding the wire conductor together with the surface of the substrate. The latter will be the case, for example, when the substrate material is a fleece-type or woven-fabric-type support.
Particularly in the course of the manufacture of paper bands or card bands such as are used, for example, for identifying luggage, the connection of the wire conductor to the surface of the substrate via a layer of adhesive between the wire conductor and the surface of the substrate has proved to be advantageous. In this case the wire conductor comes into close contact against the surface of the substrate in a peripheral region via the layer of adhesive. If the wire conductor is provided with a suitable surface coating, for example baking lacquer, the layer of adhesive may be formed from the surface coating.
With the application of the process as described above, the use of a thermocompression process for connecting the initial region of the coil and the final region of the coil to the terminal areas of the chip unit has proved to be particularly effective.
It is possible for a further increase in the effectiveness of the application of the process as described above to be achieved if a plurality of card modules are manufactured at the same time in such a way that in a feed phase a plurality of substrates arranged collected together in a yield are supplied to a card-module production device comprising a plurality of wiring devices and connecting devices and subsequently in the wiring phase a plurality of coils are formed simultaneously on substrates arranged in a row, then in the connection phase a plurality of chip units are connected via their terminal areas to the coils and finally in a separation phase a separation of the card modules from the composite yield takes place.
Furthermore, an application of the process for the manufacture of a rotationally symmetrical coil bobbin has proved advantageous wherein the wire-shaped conductor is wired on a substrate taking the form of a winding support and rotating relative to the wiring device. For the purpose of establishing the relative rotation there is the possibility either to cause the substrate to rotate about its longitudinal axis in the case of a stationary wiring device or, in the case of a stationary substrate, to move the wiring device on a trajectory about the longitudinal axis of the substrate, or even to superimpose the two aforementioned types of motion.
The aforementioned application of the process enters into consideration in particular for the manufacture of a moving coil of a loudspeaker unit that is integrally connected to a vibrating diaphragm.
According to another application of the process the process serves to wire a wire-shaped conductor on a substrate by means of a wiring device that subjects the wire conductor to ultrasound with a view to manufacturing a ribbon cable, whereby a number of wiring devices corresponding to the number of cable conductors desired is arranged transversely in relation to the longitudinal axis of a ribbon-shaped substrate and a relative movement between the substrate and the wiring devices takes place in the direction of the longitudinal axis of the substrate.
In order to achieve a reliable and operationally dependable contact between the wire conductor and the terminal areas of the chip unit, which are customarily constituted by aluminium surfaces, it is advantageous, particularly when use is made of a copper wire conductor, to subject the aluminium surface of the terminal areas to a preparatory treatment. With a particularly advantageous embodiment of the process according to the invention the preparatory treatment of the aluminium surface is virtually integrated into the actual connecting operationxe2x80x94that is to say, the contacting of the wire conductor with the terminal areas by virtue of the wire conductor being connected to the terminal areas by means of a connecting instrument taking the form of an ultrasonic instrument. In this case an oxide layer disposed on the aluminium surface is eliminated mechanically by subjecting the oxide layer to the ultrasonic vibrations of the ultrasonic instrument. This manner of cleansing the aluminium surfaces of the oxide layer, which takes place substantially at the same time as the actual connecting operation, has the particular advantage that with regard to shielding the connecting points from environmental influencesxe2x80x94by creating an inert or reducing atmosphere, for examplexe2x80x94it is possible to dispense with special measures intended to prevent the formation of a fresh oxide layer prior to implementation of the connecting operation.
If, on the other hand, as an alternative to the afore-mentioned ultrasonically induced removal of the oxide layer in conjunction with an ultrasonic connecting operation a preparatory treatment or cleansing process is chosen that is decoupled from the actual connecting operation, the connecting operation itself can be carried out in an inert or reducing atmosphere.
The use of etching processes that have great selectivity proves to be particularly advantageous for the purpose of cleansing the aluminium surfaces pertaining to the terminal areas of oxide layers. An example of dry-etching processes is ion-beam etching. But the use of processes that can be implemented easily, such as wet etching or oxide-layer removal by laser treatment, in particular by excimer-laser treatment, is also advantageous.
With a view to preventing renewed oxidation of the aluminium surface there is also the possibility of providing the aluminium surface with a multilayered contact metallisation having a zincate layer applied to the aluminium surface by way of intermediate layer and having an interconnect layer which is disposed on said zincate layer and which is provided for making contact with the wire conductor. In this case the zincate layer serves primarily to eliminate the oxide layer on the aluminium surface, and the interconnect layer, which may for instance consist of nickel or palladium or corresponding alloys, serves to improve the adhesion to the copper wires which are used as a rule by way of wire conductors.
In the case where use is made of an ultrasonic instrument for establishing the connection between the wire conductor and the terminal areas it proves to be particularly advantageous if the vibrational loading of the wire conductor which is brought about by ultrasound takes place in a plane substantially parallel to the terminal area and transverse to, for instance at right angles to, the longitudinal axis of the wire conductor. For, by virtue of the transverse flexibility of the wire conductor which is fixed on the substrate on both sides of the terminal area in the longitudinal direction the greatest possible relative movements can be achieved between the wire conductor and the aluminium surface by means of the ultrasonic loading of the wire conductor which takes place transverse to the longitudinal axis of the wire.
Irrespective of the type and manner of the preparatory treatment and also of the choice of the connecting process it is a particular advantage if by way of coil substrate use is made of a plastic support sheet which together with the coil and the chip unit forms a card inlet for the manufacture of a credit card or such like. Alternatively, differing configurations of the coil carrier are also possible which in each casexe2x80x94that is to say, irrespective of the particular configurationxe2x80x94merely have to enable secure bilateral fixation of the wire conductor relative to the terminal areas of the chip unit. By this means a virtually suspended arrangement and hence a xe2x80x9cfloating acceptancexe2x80x9d of the chip in the substrate also becomes possible. For instance, the use of a sheet of paper by way of coil substrate is also possible, in which connection the wire conductor may be fixed on the substrate via an adhesive layer which is provided on the sheet of paper and which adheres to the wire conductor, or even via an adhesive layer which is provided on the wire conductor itself, for instance a layer of baking lacquer.
Irrespective of the type of coil substrate which is used, it proves to be advantageous if the wire conductor is fixed on the substrate by means of a wiring instrument which is employed in any case for the coil-shaped arrangement of the wire conductor on the substrate and which enables a continuous or intermittent connection of the wire conductor to the surface of the substrate. In this case, particularly when use is made of plastic substrates, it proves to be advantageous if by way of wiring instrument an ultrasonic instrument is employed which enables an at least partial embedding of the cross-section of the wire conductor into the surface of the substrate and hence enables fixation with good adhesion.
A particularly good fixation of the wire conductor on the surface of the substrate and the establishment of a particularly reliable connection of the wire conductor to the terminal areas of the chip unit is possible if the ultrasonic instrument which is used for the wiring and fixation of the wire conductor on the substrate brings about a vibrational loading of the wire conductor transverse to the longitudinal axis of the wire conductor and transverse to the surface of the substrate, and if the ultrasonic instrument which is used for connecting the wire conductor to the terminal areas brings about a vibrational loading of the wire conductor in a plane substantially parallel to the substrate and transverse to the longitudinal axis of the wire conductor.
The wiring device for wiring a wire-shaped conductor on a substrate by means of ultrasound comprises a wire guide and an ultrasonic generator, whereby the ultrasonic generator is connected to the wire guide in such a way that the wire guide is stimulated to execute ultrasonic vibrations in the direction of the longitudinal axis.
It is advantageous if the device that is suitable for implementing the process according to the invention comprises an ultrasonic instrument with a vibrating punch partially encompassing the cross-section of the wire and having an ultrasonic oscillator which brings about a vibrational loading of the vibrating punch transverse to the longitudinal axis of a wire conductor that is guided by the vibrating punch.
According to a preferred embodiment of the device the ultrasonic instrument is coupled to a wire-laying instrument.
A particularly simple configuration of the device becomes possible if the ultrasonic oscillator of the ultrasonic instrument serves simultaneously for ultrasonic loading of the wiring instrument, for instance by the ultrasonic oscillator being arranged in such a way that the axis of its effective direction is variable.
It proves to be advantageous for the design of the wiring device if the latter is equipped with a wire-guidance capillary which at least in the region of a wire-guide nozzle extends in the wire guide parallel to the longitudinal axis. In this manner it is ensured that in the region of the wire-guide nozzle the axial advancing movement of the wire conductor is not impaired by ultrasonically induced transverse loads. Rather the ultrasonic loading extends in the longitudinal direction of the wire.
For the purpose of introducing the wire conductor into the wire guide, however, it proves to be advantageous if the wire guide comprises, spaced from the wire-guide nozzle, at least one wire-feed channel extending obliquely in relation to the longitudinal axis of the wire.
With a view to avoiding ultrasonically induced transverse loads on the wire conductor in the region of the wire-guide nozzle it also helps if the ultrasonic generator is arranged coaxially with respect to the wire guide.
The process according to the invention and devices that are suitable for implementing the process are elucidated below in exemplary manner on the basis of the drawings.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.